Conservapedia - User contributions [en]

Rat

2008-11-25T15:00:49Z

DianneP: /* Domesticated rats */

A '''rat''' is a medium-sized [[rodent]] found on all inhabited [[continent]]s. They live on garbage in slums and are also often known to carry disease. The [[bubonic plague]] which killed one third the population of Europe is attributed to rats which carried plague-infected
fleas living in their fur. The [[taxonomy|genus]] ''Rattus'' includes over 50 species.

Rats are capable of surviving in a wide range of different environments ranging from grasslands, forests, urban settlements, ships, and the unforgiving [[arctic]]. They tend to thrive around [[human beings]].
Rats can survive on an extremely diverse diet, including [[seed]]s, [[fruit]]s, small [[bird]]s and [[mammal]]s, scraps and even garbage.

==Domesticated rats==
Rats can be kept as pets, although it is unwise for a child to try to tame a wild rat found in a slum. Like gerbils and hamsters, they must be raised in a sterile environment before being brought into your home, lest an accidental bite infect you with a deadly disease.
They are usually kept in a [[cage]] or a [[terrarium]], sometimes with other rats or [[mice]]. Domestic rats are curious, clean, and gentle creatures with a lifespan of approximately three years.

[[category:Rodents]]

Binoculars

2008-11-24T17:04:44Z

DianneP:

[[Image:Binoculars.jpg|thumb|200px|A typical pair of general-use binoculars]]

'''Binoculars''' are an [[optics|optical]] aid used to view distant objects with both eyes, such as scenery, wildlife, or far off boats or ships. They can also be employed in basic [[astronomy]], in lieu of a [[telescope]].

They consist of twin barrels containing a system of [[lens]]es one for each eye. Because the distance between the eyes varies from person to person, there must be provision for adjusting the distance between the binoculars' eyepieces; thus the barrels are hinged together.

While most binoculars are simply designed to be purely functional, opera glasses are a kind of binoculars that are usually rather [[ornate]] in finish. They are used to improve the patron's view of the action on [[stage]]. The fancy form fits in with the formal nature of a performance and the highly decorated interior of most [[theater]]s.

==Settings==

Binoculars usually have three settings. One of them is used to change focus the binoculars on objects of different distances. The other two are personal settings which vary from person to person but which, for any person, only need to be set once and do not need to be changed subsequently.

1) A focusing knob is usually provided in the center which focuses both sides at the same time, to focus the binoculars on objects of varying distances.

2) The distance between the eyes (the ''intraocular distance'') varies from person to person. In order to allow the distance between the binocular tubes to be changed, they are hinged together at the center. Often there is a graduated scale at the hinge from which the intraocular distance can be read, usually in millimeters. If a user remembers their intraocular distance, they can quickly bring any pair of binoculars back to setting that is proper for them.

3) A second focusing adjustment is provided, usually on the right eyepiece, usually with a scale and markings in diopters. For many people, this adjustment should be set to the zero mark. Some people will find that because of refractive differences in their eyes, when the left binocular is perfectly focussed, the right binocular will be slightly out of focus. It can be brought into focus by adjusting the right eyepiece focus. Once the right eyepiece focus is set correctly, it will be correct at all distances and does not need to be adjusted again.

==Designs==
Because they are used to view terrestrial objects, the images in a pair of binoculars need to be erect, i.e. right-side-up. This poses an engineering challenge. There is a kind of telescope, the ''Galilean telescope,'' which uses only lenses and provides an erect image. Some instruments use a pair of Galilean telescopes. This design is inexpensive, can be compact, and can produce a sharp image; however, their magnification, field of view, and "exit pupil size" (which determines brightness) are all limited. This design was once popular for opera glasses, but today is found mostly in children's toy binoculars.

Most modern binoculars are ''prismatic binoculars.'' The lens systems used in them are similar to the design of a "astronomical" refracting telescope, but a system of erecting [[prism]]s is added to turn the image right side up.

In the traditional design, the presence of a prism system is visible in a dogleg appearance of the two barrels, the eyepieces being offset and out of line with the main barrel. However, in recent decades, optics firms have developed very compact prismatic binoculars with prism systems are inline with the barrels with no visible offset.

==Exit pupil size==
Binocular designs trade off between cost, size, and optical characteristics. One very important characteristic is the ''exit pupil size,'' which can be calculated by ''dividing'' the objective diameter by the magnification, an affects what uses the binoculars are good for.

*In a pair of "7x50" binoculars, which might be called "night glasses," the exit pupil is 50 mm / 7X magnification = 7.1 mm
*In a pair of "7x35" binoculars, which is a general-purpose specification, the exit pupil is 35 mm / 7X magnification = 5 mm
*In a pair of "8x20" compact binoculars, the exit pupil is 20 mm / 8X magnification is 2.5 mm

The exit pupil affects image brightness in that<ref>When looking at ordinary "extended objects," e.g. birds, targets, distant ships. The rules are different for astronomical point objects like stars</ref>
*If the exit pupil is the smaller than the pupil of the eye, the image seen through the binoculars will be dimmer than the image seen with the unaided eye.
*If the exit pupil is the same ''or larger'' than pupil of the eye, the image seen through the binoculars will be ''just as bright'' as the image seen with the eye (or perhaps very slightly dimmer due to light loss in the lenses and prisms).
*The image is ''never brighter'' than the image that can be seen with the unaided eye.

The pupil of the eye varies in size depending on how bright the light is. At night, the dark-adapted eye expands to about 7 mm. In room light or shady daylight, it is about 3-4 mm. In very bright daylight it may be less than 2 mm.

What this means is that, in the examples above, night, the 7x50 "night glasses" will give a much brighter image than the other two. Under ordinary conditions, the 7x50 will not be any brighter than the 7x35s (and are considerably heavier and more expensive). And in bright daylight, there may not be any meaningful differences in brightness between the three (and if the 8x20s are slightly dimmer, that may be a good trade-off in return for their compactness and light weight).

==Warning!==
You must on no account point binoculars at the sun. If you look at the sun directly without any eye protection through binoculars you will be blinded. On a sunny day take care that the binoculars point well away from the sun.

[[Category:Technology]]
[[Category:Vision]]

Hellenistic culture

2008-11-24T17:00:22Z

DianneP:

'''Hellenistic Culture''' is a term for [[Greek]] culture. The phrase was derived from ''Hellas'' meaning Greece. In wide use during and after the conquests of [[Alexander the Great]] in which the Hellenistic Greek culture was spread. Helenistic communities and other Asian cultures adopted traits from each other. The culture was renowned for its strict code of [[ethics]], its culinary prowess, and its use of [[metal]].

== See also ==

*[[Greeks]]
*[[Oracle at Delphi]]

[[Category:Ancient Greece]]

Galápagos Islands

2008-11-24T16:54:10Z

DianneP: /* Geology */

[[Image:Blue-footed booby.jpg|right|thumb|150px|Blue-footed booby]]The '''Galápagos Islands''' is an [[archipelago]] of 17 volcanic islands, situated in the [[Pacific Ocean]] 600 miles to the west of [[Ecuador]]. They are noted for their unique animal and bird life which led the naturalist [[Charles Darwin]] to formulate his [[Theory of Natural Selection]]. The name ''Galápagos'' derives from the [[Spain|Spanish]] word for saddle, as the shape of some of the indigenous species of [[tortoise]] resembled a saddle. The official name of the islands is Archipiélago de Colón but even official government documents refer to them as the Galapagos Islands.

Their remote location meant that the islands had few visitors and almost all of the animals exhibit no natural fear of man. However, a rising population, the presence of feral pigs and goats, and the pressures of mass tourism have begun to threaten the existence of some species. On April 10, 2007 Rafael Correa Delgado the President of Ecuador issued an emergency decree<ref>[http://www.galapagos.org/news/04_2007_Decree.html] Presidential decree 4/10/2007</ref> calling for sustainable development.

The Galápagos Islands are a [[UNESCO]] [[World Heritage Site]].<ref>[http://whc.unesco.org/en/list] UNESCO World Heritage List</ref>

30,000 people live in the archipelago on 4 of the islands. Most of these are fishermen and there have been many differences of opinion between them and the National Park with regards to overfishing. To date the Galapagos sea cumber and lobster have been rendered nearly extinct due to overfishing. There is a rising trend in the illegal fishing of Sharks for their fins in recent years. Efforts to curb overfishing has led to rioting, death threats against Lonesome George and slaughter of Giant Tortises.<ref>[http://www.oceanandair.coas.oregonstate.edu/index.cfm?content.display&pageID=72] Diego Figuero, College of Oceanic and Atmospheric Sciences, Oregon State University</ref>

==Geology==
The Galápagos Islands lie above a volcanic "hot spot" (similar to the Hawaiian Islands) where the Nazca and South American plates meet. The islands are essential the tip of a giagantic shield volcano that rises up to 10000 ft above the ocean floor. As the plate moves eastwards, new volcanic cones are formed so that the eastern islands are much older and eroded than those to the west, which are still volcanically active<ref>[http://www.galapagosonline.com/nathistory/Geology/Geology.html] Galapagos Islands Geology</ref>.

==Darwin's Finches==
[[Image:Finch1.jpg|thumb|left|150px|One of Darwin's finches]]
[[Image:Finch2.jpg|thumb|right|150px|Another of Darwin's finches]]
Darwin collected many biological specimens during the [[Voyage of the Beagle]] (1831-1836), which included birds from the Galápagos Islands. These were presented to the Geological Society of London upon his return and the birds were handed to an ornithologist for classification. From the differences in the shapes of their beaks Darwin had assumed they were different types of bird (blackbirds, grosbeaks, finches) but the ornithologist classified them as being different species of ground finch. Darwin surmised that, with little competition from other birds, individual varieties had evolved to fill ecological niches to utilize a wider range of food sources. When his journal<ref>[http://www.literature.org/authors/darwin-charles/the-voyage-of-the-beagle] The Voyage of the Beagle</ref> was published in 1843, he included this knowledge, which has misled many to think that he had developed his Theory of Natural Selection during his journey.

Some Creationists claim that the different types of finch interbreed and are therefore not different species.{{fact}}
Some say it supports adaptation.<ref>http://www.answersingenesis.org/creation/v14/i3/finches.asp</ref>

==Tortoises==
[[Image:Tortoise.jpg|left|thumb|150px|Santa Cruz giant tortoise]]The larger Galápagos Islands are home to different types of giant tortoise. These were previously in great abundance numbering in the 100,000s, but with no native predators they had no natural defence mechanisms other than their hard shell. They became an easy food source for passing sailors who took them in great numbers to provide fresh meat during their journey. Owing to their smaller size the females were usually taken first as they were easier to handle. A full-grown male tortoise can weigh up to 500 lbs.

There were originally 15 different sub-species of tortoise, each found on a different island. The number of sub-species alive today is 11, the others having been rendered extinct by the combined actions of man and his imported animals<ref>Pigs, goats cows and horse ate the sparse vegetation on which the tortoises depended and crushed their eggs.</ref>. For the sub-species from Isla Pinta only one male specimen (thought to be 170 years old) survives. This is the famous "Lonesome George", who for over 30 years has refused to engage in a breeding program to try and maintain the sub-species. However, captive breeding of the other endangered sub-species has brought them back from the brink of extinction.<ref>[http://www.galapagosonline.com/nathistory/wildlife/animals/tortoise.htm]</ref>

[[Image:Marine iguana.jpg|left|thumb|150px|Marine iguana]]
[[Image:Land iguana.jpg|right|thumb|150px|Land iguana]]

==Other Animals==
The Galápagos are home to two species of large iguana. The marine iguanas are unique in being the only aquatic lizard and feed on algae. They have developed mechanisms to help them cope with the salt water and can frequently be observed snorting salt from their nostrils.

[[Image:Masked boobies.jpg|left|thumb|150px|Nazca boobies]]
[[Image:Galapagos hawk.jpg|right|thumb|150px|A juvenile Galápagos hawk]]

==Birds==
Although the Galápagos Islands lie just below the equator, a deep cold-water upwelling makes the waters around the islands extremely rich in sea-life. This provides a valuable food source for a wide range of sea birds. These include several species of [[booby|boobies]] (blue-footed, red-footed and nazca), waved [[albatross]], [[frigatebird]]s, lava [[heron]]s and the most northerly species of [[penguin]]. Inland lagoons support a colony of pink [[flamingo]]es. The Galápagos [[hawk]] is one of a few [[raptor]]s that live on the islands.

== See also ==

*[[Ming (Clam 405)]]

==References==
<small><references/></small>

[[Category:Animals]]
[[Category:Archipelagos]]

Treatise

2008-11-24T16:51:08Z

DianneP:

A '''treatise''' is a formal and systematic [[book]] or writing containing a narrative statement on a field of [[law]] or some other subject. A treatise explains a subject at length.
[[category:law]]